Android is becoming more popular in US, but there is still not so many fancy phone cases available on the market like iPhone 3G/3Gs. I found out some Iphone 3G/3Gs cases can be easily modified to fit on Nexus One, so I give it a try.
Here is the iphone 3gs case,
with the right hand side, upper and lower side opened. So you have the USB connector, power button and volume button fit for your nexus one already!
In order to use this case, we only have to drill some holes on the back, so the nexus one camera and the speaker can be used. The size of the case is already quite fit for my case:)
Here is the modified case (attached on Nexus one):